Search

We demonstrate novel configuration of mode-locked laser oscillator where a SESAM is located inside the cavity and compared the output characteristics with the laser oscillator where the SESAM at the end of the cavity.

Beam quality improvement with pump power increasing in an end-pumped laser oscillator is experimentally realized for the first time, to the best of our knowledge. The phenomenon is caused by the population-dynamic-coupled combined guiding effect, a comprehensive theoretical model of which has been well established, in agreement with the experimental results. Based on an 888 nm in-band dual-end-pumped oscillator using four tandem Nd:YVO4 crystals, the output beam quality of $$M^2$$ = 1.1/1.1 at the pump power of 25 W is degraded to $$M^2$$ = 2.5/1.8 at 75 W pumping and then improved to $$M^2$$ = 1.8/1.3 at 150 W pumping. The near-TEM $$_{00}$$ mode is obtained with the highest continuous-wave output power of 72.1 W and the optical-to-optical efficiency of 48.1%. This work demonstrates great potential to further scale the output power of end-pumped laser oscillator while keeping good beam quality.

Preface Passively Q-Switched Microchip Lasers J.J. Zayhowski Yb-Doped Solid-State Lasers and Materials Bruno Viana, Johan Petit, Romain Gaume, Philippe Goldner, Mathieu Jacquemet, Frederic Druon, Sebastien Chenais, Francois Balembois, and Patrick Georges Tunable Cr2+:ZnSe Lasers in the Mid-Infrared Alphan Sennaroglu and Umit Demirbas All-Solid-State Ultraviolet Cerium Lasers Shingo ONO, Zhenlin LIU, and Nobuhiko Sarukura Eyesafe Rare Earth Solid-State Lasers Robert C. Stoneman High-Power Neodymium Lasers Susumu Konno Ultrafast Lasers: Technology and Applications Rudiger Paschotta and Ursula Keller Multipass-Cavity Femtosecond Solid-State Lasers Alphan Sennaroglu and James G. Fujimoto Cavity-Dumped Femtosecond Laser Oscillator and Application to Waveguide Writing Alexander Killi, Max Lederer, Daniel Kopf, Uwe Morgner, Roberto Osellame, and Giulio Cerullo Solid-State Laser Technology for Optical Frequency Metrology Oliver D. Mucke, Lia Matos, and Franz X. Kartner Solid-State Ultrafast Optical Parametric Amplifiers Giulio Cerullo and Cristian Manzoni Noise of Solid-State Lasers Rudiger Paschotta, Harald R. Telle, and Ursula Keller Index

We report on the demonstration of a highly efficient SESAM mode-locked Yb:KGW bulk laser that generated 400 fs pulses with an average output power of 12 W. The optical-to-optical efficiency and the slope efficiency were estimated to be 37% and 70%, respectively.

This presentation will describe the design and construction status of a new mobile high-energy femtosecond laser systems producing 500 mJ, 100 fs pulses at 10 Hz. This facility is built into a shipping container and includes a cleanroom housing the laser system, a separate section for the beam director optics with a retractable roof, and the environmental control equipment necessary to maintain stable operation. The laser system includes several innovations to improve the utility of the system for “in field” experiments. For example, this system utilizes a fiber laser oscillator and a monolithic chirped Bragg grating stretcher to improve system robustness/size and employs software to enable remote monitoring and system control. Uniquely, this facility incorporates a precision motion-controlled gimbal altitude-azimuth mount with a coude path to enable aiming of the beam over a wide field of view. In addition to providing the ability to precisely aim at multiple targets, it is also possible to coordinate the beam with separate tracking/diagnostic sensing equipment as well as other laser systems. This mobile platform will be deployed at the Townes Institute Science and Technology Experimental Facility (TISTEF) located at the Kennedy Space Center in Florida, to utilize the 1-km secured laser propagation range and the wide array of meteorological instrumentation for atmospheric and turbulence characterization. This will provide significant new data on the propagation of high peak power ultrashort laser pulses and detailed information on the atmospheric conditions in a coastal semi-tropical environment.

A simplified one-dimensional theoretical model for free-electron laser oscillator (FELO) calculation which reserves the main physics is proposed. Instead of using traditional macroparticles sampling method, the theoretical model takes advantage of low gain theory to calculate the optical power single-pass gain in the undulator analytically, and some reasonable approximations are made to simplify the calculation of power growth in the cavity. The theoretical analysis of single-pass gain, power growth, time-dependent laser profile evolution and cavity desynchronism are accomplished more efficiently. We present the results of infrared wavelength FELO and X-ray FELO with the new model. The results are validated by simulation with GENESIS and OPC.

We demonstrate a high-power, octave-spanning, Kerr-lens mode-locked Ti:sapphire laser using double-chirped mirrors to precisely compensate for intracavity dispersion. The ultra-broadband spectrum spans from 550 nm to 1100 nm and the few-cycle pulse is as short as 6.6 fs with an average power up to 880 mW corresponding to the peak power of 1.6 MW. This is, to the best of our knowledge, the highest average output power directly achieved from an octave-spanning Ti:sapphire laser oscillator at the repetition rate of 80 MHz. In addition, the third-order harmonically mode-locked phenomenon was observed in our experiments.

The European X-ray Free-Electron Laser will generate high energy light pulses in the femto-second range. A clock signal, which synchronizes all components, is distributed via laser pulses. The accuracy of these laser pulses is crucial to achieve precise measurements which are needed to control the Free-Electron Laser. In order to reach the maximum performance, advanced model-based control approaches are used to compensate external influences. This paper shows the modeling of the Master Laser Oscillator by fractional order systems, which improve known approaches to system modeling by providing a higher accuracy.

We report results of a systematic study of the morphology of laser-written structures within transparent media like fused silica, borosilicate glass (BK7), and polymethylmethylacrylate (PMMA) using a high-energy, 5.1 MHz repetition rate, femtosecond laser oscillator. Depending on experimental conditions, both smooth channels as well as dot patterns can be laser-written. The periodicity of the written dots is readily controlled by the energy dose, a single parameter that encompasses laser energy, translation speed at fixed repetition rate, and focusing conditions. We discover the importance of the direction in which laser-writing is carried out: the periodicity of the dot patterns written at fixed energy dose but with opposite writing directions is significantly different. In PMMA, extremely large rod-like structures (∼200 µm) are observed whose formation is also dependent on writing direction. We quantify guidance of 632 nm and 830 nm light in structures written in BK7.

A titanium:sapphire laser oscillator has been built using commercially available ultra-broadband optics. It emits 1.3 nJ energy pulses, with 5.9 fs duration and a spectral bandwidth larger than oneoctave (>570-1200 nm). It is the first two-optical cycles pulse oscillator built in Spain and, given its characteristics, it will be possible to stabilize its carrier-envelope offset phase.

We demonstrate an all-fiber ultrafast ytterbium laser oscillator mode-locked by means of a nonlinear polarization evolution (NPE) method realized in polarization-maintaining (PM) fibers. A sequence of the PM fiber pieces is shown to perform NPE action while maintaining a required temporal overlap of the ordinary and extraordinary pulses propagating through it. We present details of simple numerical simulations showing the advantage of the proposed scheme of segmented PM fibers. The laser utilizing the above mentioned design which generates ultrashort pulses at a 20.54 MHz repetition rate with the dechirped pulse duration around 150 fs and a pulse energy of 0.85 nJ is also presented.

International audience; We report on our direct experimental observation of a new regime of operation of passively mode-locked fibre lasers where the laser oscillator generates pulsating solitons with extreme ratios of maximal to minimal intensities in each period of pulsations. The soliton spectra also experience large periodic broadening and compression. Spatio-temporal intensity and dispersive Fourier-transformation measurements enable us to capture such transient dynamics in real time.

Generalized Lotka–Volterra (GLV) equations are important equations used in various areas of science to describe competitive dynamics among a population of N interacting nodes in a network topology. In this Letter, we introduce a photonic network consisting of three optoelectronically cross-coupled semiconductor lasers to realize a GLV model. In such a network, the interaction of intensity and carrier inversion rates, as well as phases of laser oscillator nodes, result in various dynamics. We study the influence of asymmetric coupling strength and frequency detuning between semiconductor lasers and show that inhibitory asymmetric coupling is required to achieve consecutive amplitude oscillations of the laser nodes. These studies were motivated primarily by the dynamical models used to model brain cognitive activities and their correspondence with dynamics obtained among coupled laser oscillators.

A stable pulse-burst GdVO4/Nd:GdVO4 laser oscillator with repetition rate up to 500kHz is demonstrated by use of a pulsed diode-laser of Stabilized Wavelength 879nm as the pump source. While the pulsed 879nm LD was operated at the repetition rate of 100Hz and the pump duration was 1ms, the different output characteristics of pulse-burst GdVO 4 /Nd:GdVO 4 laser were obtained by adjusting the repetition rate of A-O Q-switch. When the total pump energy was 120mJ, the pulse number of 100, 200 and 500, the burst energy of 25mJ, 35mJ and 40mJ, the pulse width of 8.5ns, 12ns and 27ns were achieved at repetition rate of 100kHz, 200kHz and 500kHz, respectively. The relative single pulse energies were reached to 250μJ at 100kHz, 175μJ at 200kHz and 80μJ at 500kHz. The peak powers were reached to 29.4kW at 100kHz, 14.6kW at 200kHz and 3.0kW at 500kHz. The M 2 factor was measure to 1.4.

The Lasers and Electro-Optics Branch at Goddard Space Flight Center has been tasked with building the Lasers for the Global Ecosystems Dynamics Investigation (GEDI) Lidar Mission, to be installed on the Japanese Experiment Module (JEM) on the International Space Station (ISS)1. GEDI will use three NASA-developed lasers, each coupled with a Beam Dithering Unit (BDU) to produce three sets of staggered footprints on the Earth's surface to accurately measure global biomass. We will report on the design, assembly progress, test results, and delivery process of this laser system.

Experimental results of a study on the wavelength dependence and the dynamic range of the quadratic response of commercial grade light emitting diodes (LEDs) are reported over a broad spectral range of 680 nm to 1080 nm using ~ 100 fs duration laser pulses from cw mode locked laser oscillator. A large dynamic range of the quadratic response has been demonstrated in a reverse biased LED. The observed dynamic range compares well with that obtained using a biased photomultiplier tube with large internal gain.

A simple Herriott multipass-type femtosecond laser oscillator based on only two notched mirrors without any compensator for q-preserving is presented. Due to the notches, the Herriott multipass cavity acts as a lens with a large effective focal length and is not strict for q-preserving. It is shown that the Kerr-lens mode-locked condition in the Herriott multipass cavity can be retained by using the ABCD transfer matrix containing a self-focusing effect. In this oscillator, we obtained an output power of 2.26 W at a repetition rate of 13.16 MHz and a pulse width of 26 fs, corresponding to an output energy of 172 nJ.

Bound states of femtosecond solitons are generated and controlled in a commercial sub-10 fs Kerr-lens mode-locked ultrashort oscillator. Using real-time time-stretch interferometry, we resolve the resonance of vibrating soliton molecules and demonstrate all-optical switching between stable bound-states of different binding distance.

In this paper, we present the concept of a microelectromechanical systems ring laser gyroscope (MEMS-RLG) and its optical components. MEMS-RLG has a semiconductor optical amplifier (SOA) enclosed with mirrors that form an optical loop for an external laser oscillator in free space. To confirm the feasibility of MEMS-RLGs, we constructed an experimental device with commercially available SOA and mirrors for external oscillation. We also show the fabrication and characteristics of optical components such as movable mirrors and a lens-positioning device, which are required for a miniaturized MEMS-RLG.

We have demonstrated a high-power laser oscillator with end-cooling using a sapphire-sandwiched Yb:YAG disk at near liquid nitrogen temperature. An output power of 75 W with a near-diffraction-limited beam was obtained from a 0.6-mm thick activemedium. The slope efficiency and themaximum optical–optical efficiency were 80 and 70%, respectively, with respect to absorbed pump power.

A sub-50-fs diode-pumped Yb:CALGO laser oscillator was demonstrated. The highest peak power achieved for 48-fs pulses directly from the oscillator was 1.6 MW. The shortest generated pulses were 40-fs with 177 kW of peak power.

In this paper we demonstrate that balanced optical-microwave phase detectors (BOMPD) are able to provide a robust long-term optical-RF synchronization with sub-femtosecond residual timing drift over 24 hours in laboratory conditions without active temperature control of optical and electronic paths. Moreover, 10.833 GHz Sapphire-loaded cavity oscillator (SLCO) was successfully disciplined by 216.66 MHz laser oscillator using theBOMPD which resulted in a sub-femtosecond RMS jitter integrated from 1 Hz to 1 MHz.

We propose a new method for the determination of the pumping coefficient dependence upon the variation of the flashlamp opacity in a pulsed Nd:YAG laser oscillator which cannot be determined by existing methods. The method that we propose is based on the measure of the build-up time during which the excited-state population is being pumped up to its threshold lasing value.

Abutment tooth movement was analyzed in vivo by improving the six-degree of freedom tooth movement tracking device which had been developed by Imamura.The results obtained were as follows:I. On the measurement device1) The laser oscillator unit became to be lighter at only 15gr including the crown-holder attached to the abutment tooth through replacing the beam spliter to a half-prism.2) Making the three PSDs smaller and shortening the distance of each PSD enabled to measure the abutment tooth movement under room lights of a dental office.3) Three percent of magnifying figures were obtained at the point of 2 mm from the middle point of PSD on the x-axis and the y-axis respectively. Through improving each PSD to be able to easily slide up and down and rotate, acuurate data can be obtained anytime without any distortion.II. On results measured by utilizing the device.1) Even after complete occlusal equilibration, large inclination was recognized on the abutment tooth at swallowing strongly. Especially inclination of Kt which is considered to be a rigid support type was significantly larger than that of Ak (p

To construct a removable partial denture for a Kennedy class I mandibular case remaining only two canines and four incisors is not so difficult. However, to give the patient a satisfaction with the proshesis in a long period and to maintain the health of the abutment teeth and the surround tissues is very difficult, because the lingual surfaces of the abutment teeth such as canines and incisors incline toward the roots, and can not be securred of a strong support.In this experiment, most popular five types of rest were compared to choose the best design of rest on inclination that gives great hazards to the abutment teeth and the surrounding tissues.The movements of the abutment tooth (3 ?? ) with each rest design when crushing down test food were measured by using a laser oscillator unit and a photosensor unit consist of a position sensitive detector and a signal processing circuit which were developed by Imamura, and the measured values were reciprocally compared through the statistical analysis.The results obtained were as follows:1. Inclination degree was the greatest in Design 5, and it was 1.64 times of that of control (Design 1), and Design 2 was 1.22 times that of control. Inclinations of abutment tooth with Design 3 and 4 were smaller than that of control and 0.85 times that of control. However, there were no significant differenced between each design and control or between mutual rests.2. Design 1: The degree of inclination when loading in state without any food between upper and lower dental arches was significantly larger than those under other conditions (p

An experimental and theoretical study of a high repetition rate laser source operating on a novel mode-locking technique is presented. This technique relies on the fast saturation and recovery of a semiconductor optical amplifier induced by an external optical pulse and has been used to obtain 4.3 ps pulses at 20 GHz. A complete mathematical model of the fiber ring laser is presented describing the mode-locking process in the laser oscillator and providing solutions for the steady-state mode-locked pulse profile. The critical parameters of the system are defined and analyzed and their impact on the formation of the mode-locked pulses is examined. The comparison between the theoretical results and the experimental data reveals very good agreement and has allowed the optimization of the performance of the system in terms of its critical parameters.

Feedback control of cavity detuning length in a short-pulse free-electron laser oscillator system is suggested and numerical simulation results are presented. By changing the detuning length with reference to the position of the optical pulse at the end of every pass, the system operation is very stable, and very high power and comparably good spectral characteristics have been achieved. Feasibility of this scheme is also discussed.

A passive mode-locking technique with an inhomogeneously broadened absorber is described theoretically in a regime in which the duration of the generated pulse is less than the polarization decay time. The possibility of generation of self-induced-transparency solitons directly from the laser oscillator is shown. A new effect, instability due to spectral hole-burning, is discussed. A comparison with experiment is given.

We report on the fiber-based amplification of a cavity-dumped Yb:KYW laser oscillator. With this system, we were able to generate 420-fs pulses with pulse energies of 9 μJ at a 1-MHz repetition rate.

A method for increasing the output power of a phase conjugated oscillator (PCO) by using two stimulated-Brillouin-scattering (SBS) cells is described. The average power has been more than doubled and the peak power has been increased by twenty times compared to the single-SBS-cell PCO. Near unity beam quality has been measured.

We simulate the transient behaviour of a self-starting holographic laser oscillator using a numerical model which can account, to arbitrary strength, for one, two and four gain gratings within the saturable amplifying medium. The dependence of output energy on parameters such as intracavity gain and output coupler reflectivity is investigated, thereby enabling the optimisation of extraction efficiency and the understanding of oscillation and grating dynamics.

Kerr-lens mode-locking (KLM) in Yb:CALGO has been demonstrated by means of a high-brightness optical pumping with an Yb:fiber laser. Stable 37 fs pulses are produced with an average power of 1.5 W.

We report on Kerr lens mode locking of Yb:CALGO by means of high-brightness optical pumping with a diffraction limited fibre laser. Various cavity configurations have been investigated to deliver sub-40 fs pulses at watt level and pulse duration as short as 32 fs.

Lidar is one of the key sensors to understand global atmospheric environment, so lidar is one of the candidates to be flown on future earth observation satellites. But spaceborne lidar is our first trial and we have some technical issues to resolve before establishing operational sensor. So we start development of the Spaceborne Lidar Experimental Model as a first step of lidar program of NASDA. The Spaceborne Lidar Experimental Model will be launched in early 2001. The purpose of the Spaceborne Lidar Experiment is technological demonstration of system design and critical components to apply to future operational sensor. And we demonstrate availability of lidar observation data and scientific value. There are some critical points to resolve such as (1) thermal design of laser oscillator which remove locally-generated-heat effectively and (2) mirror design with little distortion.

A solid-state laser resonator is demonstrated which incorporates a real-time holographic element that corrects dynamically for both intracavity phase and polarization distortions. The results are compared with those from a holographic laser which corrects for phase distortions but does not include polarization correction. In comparison to the latter system the polarization correcting laser displays superior performance and notably, an output beam quality and energy that is insensitive to changes in intracavity polarization distortions.

The nonstationary dynamics of the free-electron laser oscillator with a low-Q cavity and a broad feedback frequency bandwidth is studied. A method for accounting for the feedback frequency dispersion within the framework of the spatio-temporal approach is proposed. It is shown that broadband dispersion changes the dynamics of the laser excitation, even when its bandwidth is large compared with the amplification bandwidth. Because of the reduction of the number of competing longitudinal modes, the transient time is significantly shortened. Moreover, the current threshold of stability of the single-frequency generation is considerably enlarged.

We report on the generation of extreme ultraviolet radiation utilizing the plasmonic field enhancement in arrays of bow-tie gold optical antennae. Furthermore, their suitability to support high-order harmonic generation is examined by means of finite-difference time-domain calculations and experiments. Particular emphasis is paid to the thermal properties, which become significant at the employed peak intensities. A damage threshold depending on the antenna length is predicted and confirmed by our experimental findings. Moreover, the gas density in the vicinity of the antennae is characterized experimentally to determine the number of atoms contributing to the measured radiation, which is almost an order of magnitude larger than previously reported. DFG/EXC/QUEST

Frequency combs can be used directly, for example as a highly precise spectroscopic light source. They can also be used indirectly, as a bridge between devices whose high precision requirements would normally make them incompatible. Here, we demonstrate two ways that a frequency comb enables new technologies by matching optical cavities. One cavity is the laser oscillator. A second cavity is a low-threshold doubly-resonant optical parametric oscillator (OPO). Extending optical referencing to the doubly-resonant OPO turns the otherwise unstable device into an extremely precise midinfrared frequency comb. Another cavity is an optical enhancement cavity for amplifying spectral absorption in a gas. With the high speed of a graphene-modulated frequency comb, we can couple a frequency comb directly into a high-finesse cavity for trace gas detection.

We investigate the thresholds of periodic and chaotic oscillations in a free-electron laser oscillator by using self-consistent time-dependent one-dimensional Maxwell-Lorentz equations. We consider a Raman-like case where the space charge effects are pronounced. From the parameter dependence of the limit-cycle oscillation frequency, we modify the previous fitting formulas and specify the regimes for the periodic limit-cycle oscillation and for the chaotic oscillation.

Here, we present a description of an inexpensive ultrafast self-starting passively mode-locked laser oscillator that can be constructed using widely available off-the-shelf optical components. Such a laser system can be used to teach students the principles of solid state laser engineering, demonstrate a number of nonlinear optical phenomena, and perform qualitative and quantitative comparisons between numerical laser modeling and experimental results.